Crude oils and other heavier petroleum fractions often contain paraffinic materials. The major constituents of these paraffinic waxes contain long-chain normal alkyl regions. These waxy compounds will readily crystallize out upon cooling of the oil fraction containing them. This can result in deposits which obstruct the flow of oilfield production fluids. These deposits need to be removed from the flowlines and vessels to achieve more production of petroleum.
Various means for removing paraffin wax have been utilized. Sulfur trioxide has been used to contact the paraffin and form a dispersible material that is removed with an aqueous liquid and a surfactant. Other solvents and dispersants such as a copolymer of a primary alcohol and ethylene oxide with sodium silicate and N-substituted succinimide ethers have been tried. U.S. Pat. No. 4,813,482 teaches injecting a mixture of an alkyl or aralkyl polyoxyalkylene phosphate ester surfactant in free acid form or as a salt with a mutual solvent and water to remove paraffin deposits. This mixture must be at a temperature greater than the melting point of the wax to be effective. Since none of these processes melt the wax, they can only slowly eat away at its surface. This is not fast enough at most realistic surface to volume ratios. Furthermore, they create dispersions in water which must be disposed of or otherwise expensively dealt with.
U.S. Pat. No. 4,755,230 teaches the use of inorganic nitrate/nitrite compounds in redox reactions which result in an exotherm which melts the paraffin deposit and generates nitrogen gas. This does melt the wax, but requires the use of water to deliver the reactants, so that if the wax disperses at all, which it may well not, it does so into water which then must be expensively dealt with. Furthermore, gas generating redox reactions tend to be self accelerating, rendering them at best kinetically unpredictable, at worst explosive.